JP3481401B2 - Power supply device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with an image carrier contact member such as a charging member or a transfer member, to which electric power is supplied from a power source in a state of being in contact with the image carrier directly or through a sheet. The present invention relates to a power supply device in which power is supplied to an image carrier contact member from a power supply via a plurality of power supply paths.

[0002]

2. Description of the Related Art For example, as shown in FIG. 3, a charging device, which is a power feeding device for charging a photosensitive member, which is an image bearing member, by feeding power to a charging member is described in JP-A-5-303263. There is something. This charging device rotatably supports a shaft portion (core metal) 32 of a charging roller 31 which is a charging member whose surface is in contact with a photosensitive drum with a bearing 33, and the bearing 33 is placed between the lower surface of an electrode 34 and the bearing 33. The interposed spring 35 urges the photosensitive drum toward the photosensitive drum (downward in the drawing).

The spring 35 is made of a conductive material. Further, the electrode 34 is connected to the power source 36. The tip 34a of the electrode 34 is the charging roller 31.
It is in direct contact with the end surface of the shaft portion 32. Thereby,
A first power supply path A is formed from the power source 36 to the shaft portion 32 of the charging roller 31 via the tip portion 34a of the electrode 34.

A second power supply path B is also formed from the power supply 36 through the electrode 34 and the spring 35 to the shaft portion 32 of the charging roller 31. According to this charging device, since the two power supply paths A and B as described above are provided, even when one of the power supply paths becomes defective, the other power supply path reliably supplies power to the charging roller 31. Can be done.

[0005]

However, in the case of the above charging device, there are some problems as described below. (1) When the charging roller 31 moves in the compression / expansion direction of the spring 35 due to the urging force of the spring 35, the contact point between the tip portion 34a of the electrode 34 and the end surface of the shaft portion 32 of the charging roller 31 changes. The contact becomes unstable. (2) The charging roller 31 may deform the electrode 34 when it moves in the vertical direction in FIG. (3) The electrode 34 may be deformed when the charging roller 31 is assembled (for example, in a unit state).

The present invention has been made in view of the above problems, and the charging is performed by the power supply in a state where the image carrier is rotated by the urging force of the urging member, either directly or through a sheet of paper. An object of the present invention is to enable stable power supply to an image carrier contact member such as a roller even if the image carrier contact member moves due to the urging force of the urging member.

[0007]

In order to achieve the above object, the present invention is rotatably held and brought into contact with an image carrier directly or through a sheet by an urging force of an urging member, and power is supplied from a power source. An image carrier contact member, comprising: an image carrier contact member to be supplied, wherein power is supplied from a power source to the image carrier contact member via a plurality of power supply paths, and one of the plurality of power supply paths is an image carrier contact member. A bearing made of a conductive material that rotatably supports the shaft of is urged toward the image carrier.
To via the power supply is the member is a power supply path for supplying power to the shaft portion from the power supply, the other one feeding path, upper
Serial is another member and the member to be powered, one end portion directly contacts with the shaft portion, the other end portion is interposed in contact with its powered by member between the members to be the bearing and the feeding The power is supplied from the power source through a power supply member that is in contact with the bearing.
Is a power feeding path that directly reaches the shaft portion through a member, and is configured to move integrally with the shaft portion and the bearing while the power feeding member is in contact with the shaft portion of the image carrier contact member. .

With this arrangement, even if the image carrier contact member moves toward the image carrier or moves away from the image carrier due to the urging force of the urging member or the like. A power feeding member forming a power feeding path in a state of being in direct contact with the shaft portion of the image carrier contact member, and a bearing for rotatably supporting the shaft portion of the image carrier contact member and the image carrier contact member. Since they move together, poor conduction is less likely to occur. Therefore, stable power can be supplied from the power source to the image carrier contact member.

The power supply member may be a leaf spring. Then, one end of the material directly contacts the shaft of the image carrier contact member due to the spring property of the material itself, so that more reliable contact can be obtained. Further, it is preferable that the member to be fed from the power source is formed of an elastic member and the feeding member is pressed against the bearing by the urging force of the elastic member. Then, the power feeding member is pressed against the bearing that rotatably supports the image carrier contact member by the urging force of the elastic member, so that a special component for stopping the power feeding member on the bearing is not particularly required. Therefore, the number of parts can be reduced. Moreover, the assembling property and the disassembling property are improved.

The image bearing member contact member may be a charging member that charges the surface of the image bearing member. By doing so, the charging device is less likely to cause conduction failure, so that a more stable image can be provided. Further, the image carrier contact member may be a transfer member for transferring the toner image formed on the surface of the image carrier to a sheet. that way,
Since the image can be transferred more stably, the image quality can be improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a charging device showing an embodiment in which a power feeding device according to the present invention is applied to a charging device, and FIG. 2 is a schematic diagram showing the periphery of an image forming unit of an image forming apparatus provided with the charging device. is there. A copying machine, which is an image forming apparatus showing the periphery of an image forming unit in FIG. 2, is of a contact charging type having a charging roller 2 which is an image carrier contact member for charging a photosensitive drum (image carrier) 1 in a contact state. In the image forming apparatus, the charging roller 2 is rotated at a constant speed in the arrow E direction while being rotated while being in contact with the photosensitive drum 1 rotating at a predetermined peripheral speed in the arrow C direction in FIG. The surface 1a of the body drum 1 is uniformly charged to a predetermined potential.

The photosensitive drum 1 is driven by a motor which is rotationally driven via a drum driving timing belt and a drum driving pulley (both not shown), and a charging roller 2 is provided on the surface 1a thereof with conductive pressure. Due to the urging force of the spring 12, for example, a contact pressure of 10 g / cm (substantially linear contact)
It is pressed in.

Around the photoconductor drum 1, a developing device 6 in addition to the charging roller 2, a transfer roller 7 constituting a transfer device, and a cleaning unit 8 are provided, respectively. The light is the surface 1a of the photosensitive drum 1.
When the charging surface is exposed to light, the charging surface uniformly charged by the charging roller 2 is exposed to form an electrostatic latent image thereon, and the electrostatic latent image is developed by the toner supplied by the developing sleeve 6a of the developing device 6 to form the toner. It becomes an image (visible image).

On the other hand, the transfer paper P, which is a paper stored in a paper feed cassette (not shown), is sent out one by one by a paper feed roller rotating at a predetermined timing, and the transfer paper P is pressed against the registration roller 13 and it. After being temporarily stopped between the rotating pressure roller 14 and the timing adjustment, the sheet is conveyed toward the transfer portion provided with the transfer roller 7 at an accurate timing that matches the toner image on the photosensitive drum 1. It

On the transfer paper P, a toner image is transferred to the upper surface side in FIG. 2, the toner image is separated from the photosensitive drum 1 and conveyed to a fixing device (not shown), where the toner is fixed and then discharged to the outside of the device. It is ejected to a paper tray or the like. Then, the residual toner remaining on the photoconductor drum 1 after the transfer is completed and foreign matters such as paper dust are removed by the cleaning blade 8a provided in the cleaning unit 8, and the residual potential left on the photoconductor drum 1 is removed. It is removed by a charge eliminating lamp (not shown) to prepare for the next charging by the charging roller 2.

As shown in FIG. 1, the charging roller 2 has a conductive elastic layer 16 made of rubber integrally attached to the outside of a shaft (conductive core metal) 15 made of, for example, stainless (SUS). is there. Then, the bearing 1 in which the small-diameter portions 15a, 15a formed at both ends of the shaft portion 15 are formed of a conductive material
7, 17 are rotatably supported (only one shaft end side is visible in FIG. 1), and each bearing 17 is electrically fed by a conductive pressure spring (elastic member) 12 which is a member to which the photosensitive drum 1 is directed. The charging roller 2 is urged to contact the surface 1a of the photosensitive drum 1 in a state where the axis of the charging roller 2 is parallel to the axial line of the photosensitive drum 1.

The charging roller 2 is formed as a unit with the charging case 11. An L-shaped bent electrode plate 18 is fixed to the charging case 11, and a convex spring receiver 18a is formed on the lower surface of one end of the electrode plate 18.
It is held by fitting one end of the conductive pressure spring 12 into. In addition, the charging case 11 is
Small diameter portions 15a, 15a at both ends of the shaft portion 15 of the charging roller 2
Bearings 17 and 17 (only one side of which is shown in FIG. 1) for rotatably supporting each of them are held movably in the vertical direction in FIG.

The bearing 17 can be moved by a predetermined amount only in the direction in which the charging roller 2 approaches and separates from the photosensitive drum 1 by a bearing holding groove (not shown) formed in the charging case 11. Then, a spring receiver 17a is provided on the upper surface of the bearing 17, and a leaf spring 19 which is a power feeding member made of a conductive material is fitted into the hole portion formed at the left end in FIG. It is installed by doing so.

The leaf spring 19 has an arcuate slidable contact portion 19b formed at the right end in FIG. 1, and the slidable contact portion 19a.
Is in direct contact with the shaft portion 15 of the charging roller 2. In addition, the other end portion fitted into the spring receiver 17a of the bearing 17 is
The leaf spring 19 is interposed between the bearing 17 and the conductive pressure spring 12 so that the leaf spring 19 is pressed against and fixed to the upper surface of the bearing 17 by the biasing force of the conductive pressure spring 12.

As described above, the charging roller 2 includes the charging case 1
1 and other various parts, the unit is formed in a unit, and in the state where the leaf spring 19 is in contact with the shaft portion 15 of the charging roller 2, the shaft portion 15 and the bearing 17 are integrated in the vertical direction in FIG. It is designed to move. One end of a main body side application spring 21 is pressed against the electrode plate 18 fixed to the charging case 11, and the other end of the main body side application spring 21 is held by a spring receiver of the main body side receptacle 22.

Further, the main body side receptacle 22 is connected to the main body power source 20 so that the main body power source 20 supplies power (bias is applied) to the charging roller 2 through two power feeding paths. . That is, one of the two power supply paths passes from the main body power supply 20 through the main body side receptacle 22 and the main body side application spring 21, the electrode plate 18 of the charging roller unit, the conductive pressure spring 12, and the bearing 17. Is a power feeding path for feeding power to the shaft portion 15.

Another power feeding path is the same power feeding path from the main body power source 20 to the conductive pressure spring 12, one end of which directly contacts the shaft portion 15, and the other end of which is the bearing 1.
Bearing 1 in the state of being interposed between 7 and the main body side application spring 21.
7, the shaft portion 15 of the charging roller 2 passes through the leaf spring 19 that comes into contact with
Is a power supply route to. As described above, in this charging device (power supply device), the power supply from the main body power supply 20 to the charging roller 2 is performed by providing the two power supply paths, so that one of the power supply paths is temporarily defective in conduction. Even in this case, the other power feeding path can reliably feed power to the charging roller 2, so that a more stable image can be provided.

That is, when power is being supplied to the charging roller 2, the charging roller 2 is rotating together with the photosensitive drum 1. At that time, the roundness of the charging roller 2 and the photosensitive drum 1 is Alternatively, the charging roller 2 moves up and down in FIG. 1 due to the play of the supporting portion that rotatably supports these rotating bodies, the urging force of the conductive pressure spring 12 or the vibration of the drive system of the apparatus. It may happen.

In this case, in the conventional charging device, as described with reference to FIG. 3, the electrode for supplying power to the charging roller is temporarily separated from the end surface of the shaft portion (core metal) of the charging roller. This could make the contact unstable. Also, when the charging roller moves up and down, there is a risk of deforming the electrode in contact with the end surface,
There is also a risk that the electrodes may be deformed when the charging roller is set in the unit state.

However, according to the charging device of this embodiment, even if the charging roller 2 may move in the vertical direction in FIG. 1, one side of the charging roller 2 is in direct contact with the shaft portion 15 of the charging roller 2. Since the leaf spring 19 constituting the power feeding path of (1) moves integrally with the shaft portion 15 of the charging roller 2 and the bearing 17 rotatably supporting the small diameter portion 15a of the shaft portion 15, Since conduction failure is unlikely to occur at the contact points, stable power supply can be performed from the main body power supply 20 to the charging roller 2.

Further, in this embodiment, since the feeding member contacting the bearing 17 is the leaf spring 19, the sliding contact portion 19a formed on one end side is the shaft portion of the charging roller 2 due to the spring property of the material itself. A direct contact with 15 results in a more reliable contact. Since the leaf spring 19 is pressed against the bearing 17 by the urging force of the conductive pressure spring 12, it is not necessary to provide a dedicated fixing part for fixing the leaf spring 19 to the bearing 17. Therefore, the number of parts can be reduced, and the assembling property and the disassembling property are improved.

An example in which the power supply device according to the present invention is applied to a charging device of an image forming apparatus has been described above, but the power supply device according to the present invention can also be applied to a transfer device. In that case, the image carrier contact member is
The transfer roller 7 transfers the toner image formed on the surface 1a of the photosensitive drum 1 to the transfer paper P described above. By doing so, the image can be more stably transferred, and thus the image quality can be improved.

[0028]

As described above, according to the present invention, the charging roller that is supplied with power from the power source while being rotated by the urging force of the urging member is brought into contact with the image carrier directly or through the paper and is rotated. Image carrier contact members such as transfer rollers
Even if the power supply member moves due to the urging force of the urging member or the like, it moves integrally with a bearing that rotatably supports the shaft portion and the image carrier contact member while the power supply member is in contact with the shaft portion of the image carrier contact member. Therefore, poor continuity hardly occurs. Therefore, stable power can be supplied from the power source to the image carrier contact member. In addition, there is no fear of deforming other parts such as electrodes.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a charging device showing an embodiment example in which a power feeding device according to the present invention is applied to a charging device.

FIG. 2 is a schematic view showing the periphery of an image forming unit of an image forming apparatus similarly provided with the charging device.

FIG. 3 is a schematic diagram showing a part of a charging device that is a power feeding device that charges a photosensitive drum that is an image carrier by feeding power to a conventional charging member.

[Explanation of symbols]

1: Photosensitive drum (image bearing member) 1a: Surface 2: Charging roller (contact member for image carrier) 7: Transfer roller (image carrier contact member) 12: Conductive pressure spring (member supplied from the power supply) 15: Shaft 17: Bearing 19: Leaf spring (power supply member) 20: Main body power supply

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Claims (5)

(57) [Claims] 1. An image carrier contact member, which is rotatably held and is brought into contact with the image carrier directly or via a sheet by an urging force of an urging member, and is supplied with power from a power source, the image carrier contact in the power supply device power is supplied from the power supply through a plurality of power supply path to the member, one of said plurality of feed paths, formed of a conductive material which rotatably supports the shaft portion of the image bearing member contact member A member to be energized for urging the fixed bearing toward the image carrier.
Is a power feeding path for feeding power from the power source to the shaft section via another power feeding path, and the other one power feeding path is a member different from the member to be fed with power.
There, against the member to be the power supply between the one end in direct contact with the shaft portion, a member other end portion is the power supply and the bearing
Before interposed in touch state through the power supply member in contact with the bearing
Through the member to be the power from the serial supply a direct <br/> lead feed path to said shaft portion, the shaft portion and the bearing in a state where the power supply member is in contact with the shaft portion of the image bearing member contact member A power supply device characterized in that it is designed to move integrally with the power supply device. 2. The power feeding device according to claim 1, wherein the power feeding member is a leaf spring. 3. The member according to claim 1, wherein the member to be fed from the power source is formed of an elastic member, and the feeding member is pressed against the bearing by the urging force of the elastic member. Power supply device. 4. The power feeding device according to claim 1, wherein the image carrier contact member is a charging member that charges the surface of the image carrier. 5. The image carrier contact member is a transfer member for transferring a toner image formed on the surface of the image carrier to a sheet, according to any one of claims 1 to 3. The power supply device described.